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Had noticed recently a whistling sound that was noticeable as car came to a stop and was idling. Thought at first may be a belt or tensioner. However, seems sound can only be heard from inside cabin. One week earlier the "check engine soon" light had come on then went out a few days later. Car has been running great as always. Came back on today. Code: P0440 Evaporative Emission System. Was the intermittent whistle sound only heard from cabin related to this DTC? Sounds like something coming from back of engine close to vents. Any thoughts greatly appreciated.....Chris

That sound you have is coming below car somewhere between engine and transmission.
You need to change OSV (oil separator valve) is located at the back of air intake manifold...
Part is around $100 and here is a link how you can change that part...
I was do that and is work 100%...
Here is a link how to do that by yourself http://www.bimmerboard.com/forums/posts/233246